.loading {
    width: 50px;
    height: 50px;
    border: 5px solid #000;
    border-top-color: transparent;
    border-radius: 100%;

    animation: circle infinite 0.75s linear;
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    margin: auto;
}

@keyframes circle {
    0% {
        transform: rotate(0);
    }

    100% {
        transform: rotate(360deg);
    }
}